CBSE 2025 · Region 1 · Set 3 · Q23 · 3 marks

Calculate $\displaystyle \Delta_{\mathrm{r}} \mathrm{G}^{\circ}$ and $\displaystyle \log \mathrm{K}_{\mathrm{C}}$ of the reaction. $\displaystyle 3$ \[2 \mathrm{Cr}(\mathrm{~s})+3 \mathrm{Cd}^{2+}(\mathrm{aq}) \longrightarrow 2 \mathrm{Cr}^{3+}(\mathrm{aq})+3 \mathrm{Cd}(\mathrm{~s}) \] Given $\displaystyle \mathrm{E}_{\mathrm{Cr}^{3+} / \mathrm{Cr}}^{\circ}=-0.74 \mathrm{~V}$ \[\mathrm{E}_{\mathrm{Cd}^{2+} / \mathrm{Cd}}^{\circ}=-0.40 \mathrm{~V} \] $\displaystyle \left[\mathrm{R}=8.314 \mathrm{~J} \mathrm{~K}^{-1} \mathrm{~mol}^{-1}, \mathrm{~F}=96500 \mathrm{C} \mathrm{mol}^{-1}\right]$

CBSE Class 12 Chemistry past-paper question from the 2025board exam, with the answer as CBSE’s own marking scheme gives it. Where our answers come from.